Process and apparatus for production of artificial thread



June 30, 1936- P. E. HARRISON PROCESS AND APPARATUS FOR PRODUCTION OF ARTIFICIAL THREAD 1934 2 Sheets-Sheet l I Filed Oct. 6,

BNVENTOR. Paul E. flaw/5071 v ATTOR EY.

Jim: 30, 1936. P. E. HARRISON v PROCESS AND APP ARATUS FOR PRODUCTION OF ARTIFICIAL THREAD Filed Oct. 6, 1954 2 Sheets-Sheet 2 a 9 34- I I" A5 I I f; J m f %Z is W 3| d 4 35 r 4 2O 13 f INVENTOR. Paul E. fizzrrison BY w 9% ATTD NEY.

Patented June 30, 1936 UNITED STATES PROCESS ,AND APPARATUS FOR PRODUC- TION OF ARTIFICIAL THREAD Paul E. Harrison, Dover, N. H., assignor to Du Pont Rayon Company, New York, N. Y., a corporation of Delaware Application October 6, 1934, Serial No. 747,201

9 Claims.

This invention relates to humidification, and more particularly it relates to a method for humidifying spinning bucket compartments and apparatus for carrying out such method. The

invention is concerned primarily with the prevention of crystal formation on spinning buckets and in bucket compartments used in connection with the manufacture of artificial thread. The invention will be described in connection with the manufacture of viscose rayon, it being understood that it is not limited thereto but may be used in the manufacture of anyartificial thread in the spinning of which it is desired to maintain a relatively high humidity in the bucket compartment.

During one step in the manufacture of viscose rayon' by the bucket spinning process, the newly formed thread, still wet with. coagulating liquor, is wound into the form of an annular cake in the centrifugal bucket. Due to the speed; ;of the spinning bucket, a certain amount ofexcess liquid is thrown by the bucket onto the walls of the compartment in which the bucket is located. At low bucket speeds, no problem is caused by this discharge, but with high bucket speed, particularly in the spinning of fine filaments, enough liquid is evaporated todeposit salt crystals on thewalls ofthe compartment, on the bucket and on the bottom of. the compartment cover. These crystals on the bucket very materially increase the power load-necessary to drive the bucket, and furthermore the crystals from the bottom of the compartment cover often drop into the bucket and materially damage the filaments or yarn therein.

It has been proposed to minimize crystalformation in spinning bucket compartments by squirting a stream of water or steam against the sides of the bucket. This proposed method has been found to eliminate crystal growth on the outside of the bucket and on the compartment walls but it requires the passing of fluid at relatively high pressure within the bucket compartment with the consequent danger of contacting the yarn with water. If the water contacts the yarn in the bucket, it deleteriously affects its properties. Furthermore, the passing of steam or water into the bucket compartment will very materially dilute the coagulating fluid dripping from the yarn and prevent or make uneconomical the recovery thereof.

It is an object of this invention to prevent crystallization of coagulating bath liquor in a spinning bucket-compartment.

It is a further object of this invention to increase the relative humidity in a spinning bucket compartment. 7 u j A still further object of this invention is to produce high quality, artificial yarn in high speed spinning buckets. H e

Other objects of the invention will appear hereinafter.

Theobjects of this invention are accomplished in general by lowering the temperature within the spinning bucket compartment and thus iricreasing the relative humidity to a degree'which will prevent formation of crystals. This is preferably accomplished by providing a jacket or coil f adjacent the external surface of the spinning compartment andcirculating a refrigeratingfiuid or water 'at a comparatively low temperature therethrough. The details and advantages of the invention willbecome-more apparent by reference to the following detailed description taken in connection. with the accompanying illustrations, in which: r t Fig. .1 is avertical sectional view of a bucket compartment showing a bucket positioned therein. V j I Fig; 2 is a plan view, partly in section, taken on line 2-2 of Fig. 1. j I

, Fig. 3 is a vertical sectional view of a modified form of bucket compartment.

Fig.4" is a plan View, partly in section, t aken on line..4-4,-of Fig. 3. Referring to the accompanying illustrations, reference character 9 designates an enclosing structure connected to the frame 26 of the bucket spinning machine. This enclosing structure, in the instant case, has been shown as made of wood, but, obviously, this structure may be made of any desired material. Numeral l9 designates a ventilating duct which is adapted to connect a plurality of bucket compartments so as to withdraw objectionable air and vapors from the spinning compartment. At the bottom of the ventilating duct is provided a coagulating liquid drain H which serves to carry the coagulating liquid or drip from the various bucket compartments to a recovery system or to the sewer, as the case may be. The duct Ill and the drain l I extend throughout the length of the 'machine, which may comprise as many as bucket compartments. The individual bucket compartments 20 are shown as being circular in cross-sectionbut they may be of any desirable form or shape. Each bucket compartment is preferably provided with a cover l 4 having a hole I 5, which hole is positioned above the central part of the bucket IS. The thread is admitted to the bucket l9 through a traversing funnel (not shown) and which is adapted to project through said opening l5. l6 designates a driving mechanism for imparting rotation to the bucket IS, the bucket being connected to the driving mechanism by means of a shaft l8. The various bucket compartments are connected to the main air duct II! by means of ducts l3 so as to permit a certain amount of air circulation within the bucket compartments 20. These connections between the various bucket compartments and the main air duct [0 may be provided, adjacent the outlets thereof, with any suitable form of valve or damper 21 for controlling the amount of air circulation within the bucket compartment.

In the modification of the invention, as shown in Fig. 1, a plurality of coils 22 are positioned around the external surface of the bucket compartment 20, the lower coil of which is connected to a header line 23, and the upper coil of which is connected to a second header line 2|. Water at a predetermined temperature may be introduced into the header 23 through the valve 24 (Fig. 2), from which it may flow through the various coils 22 surrounding the bucket compartments to the outlet header line 21. The amount of water passed through the header 23 may be controlled by means of the valve 24; furthermore, if desired, each set of coils surrounding the individual bucket compartments may also be provided with a regulating valveysuch as that shown by 25. Should it be diff cult to obtain water at a definite'predetermined, low temperature, it is obvious that any other desired refrigerating medium can be supplied to the coils 22.

In the modification shown by Figs. 3 and 4, the bucket compartment 20 is provided with a jacket 3| spaced slightly therefrom so as to provide an annular chamber 31 surrounding the bucket compartment. The various chambers 31 surrounding the individual bucket compartments are connected to an inlet header line 33 by means of connecting conduit 35. An outlet header. line 32 is connected to the jacket 3| by means of a connecting conduit 34. The refrigerating fluid, such as water at a desired low temperature, is introduced into the inlet header line 33 through the valve 36 (Fig. 4) the refrigerating fluid'then rising in the chambers 31 surrounding the compartments until it reaches the overflow conduit line 34 by means of which it is carried to the outlet header line 32. The rate of flow of therefrigerating fluid in this case, asin the modification shown by Figs. 1 and 2, may be controlled by means of the inlet valve 36. 7

The humidiflcation system constructed in accordanoe with this invention is adapted to operate as follows: 7

The bucket 19 is rotated at high speed and thread is admitted thereto through a traversing funnel (not shown) whichis positioned concentrically with the central opening I5 in the cover 14 of the bucket compartment 20. The rotation of the bucket draws air into the compartment 20 from which it is withdrawn into the ventilating duct 10. Water or other refrigerating fluid is passed through the coils 22 or the jacketed chambers 31 of the bucket compartments, the flow of which is regulated by means of the header valve 24 or 36 or by means of the individual bucket compartment valve 25. By means, of these valves the temperature in the bucket compartments may be regulated to any desired degree, and it is preferably lowered to such an extent that the relative humidity is just high enough to prevent the formation of crystals within the bucket, the bucket compartment or on the bucket cover.

The temperature of the water or other refrigerating fluid and the amount thereof used in lowering the temperature of the bucket compartment will obviously vary between wide limits due to variations in barometric pressure, speed of spinning, acid, salt and glucose content of the coagulating bath, denier of the filaments, and circulation of air through the spinning compartments. Under ordinary conditions, the relative humidity is preferably maintained between and to prevent crystal formation, although in unusual cases, where the various factors causing crystal growth are all present under unfavorable circumstances, a higher relative humidity may be necessary. The relative humidity may be measured in a well known manner by the use of wet and dry bulb thermometers, and the temperature and/ or the rate of flow of the refrigerating medium adjusted accordingly.

Some advantages of this invention can be obtained by the use of non-circular compartments, but a round or volute compartment acts much more efilciently than a rectangular compartment, due to the fact that the air circulation within the bucket compartment can be more efliciently regulated.

Obviously the coils, jackets or connecting ducts of the apparatus should be made'of suitable corrosion-resistant material, such as for example lead, nickeLaluminum. or a suitable non-metallic substance such as a phenol-aldehyde conde'nsation product.

The supply of refrigerating medium to the coils or jackets is preferably only under suffic'ient pressure to insure a flow from the bottom header line to the top header line, which pressure'will usually not exceed a head of 1 or 2 "feet. 'On the other hand, should it be necessary to pass-a great deal of water'or other refrigerating fluid, to obtainthe necessary lowering of temperature, it may be passed to the coils or jacketsat higher pressures, for example 2-10 lbs. per square 'inch,and in such case the outlet head- 'er line may beprovided with a valve to aid in regulating the flow of the fluid.

It is'a'further advantage of this invention that a compartment may be served with substantially saturated air without bringing a humidifying liquid into it and thereby cause a dilution of the coagulating liquid. Bucket spinning machines equipped with this humidification system operate without 1 crystal formation, and as a matter of fact, this humidification system has not only prevented'crystal formation but has also caused the removal of the crystals already formed, which compares favorably with machines equipped with water or steam spraying means. By eliminating the formation of crystals on the buckets and compartment walls, the yarn is not damaged by the crystals and a lower power load on the equipment is effected. By using low pressure water'and eliminating the nozzles by which water is delivered under higher pressure, mechanical simplification is secured and diificulties are eliminated. For instance, if spray jets are used'withaccompanying high water pressure and if a bucket should fly off the spindle or burst, the jet is usually broken and the deluge of water damages the equipment and renders the rayon contacted therewith unfit for use. Other advantages of this invention are believed to be apparent.

Since it is obvious that various changes and modifications may be made in the above description and accompanying illustrations, without departing from the nature and spirit thereof, it is to be understood that the invention is not to be limited thereto except as set forth in the appended claims.

I claim:

1. In an apparatus for the manufacture of artificial threads, a plurality of individual compartments, centrifugal spinning buckets in said compartments, and refrigerating means for regulating the relative humidity of said compartments.

2. In an apparatus for the manufacture of artificial thread, a plurality of individual compartments, centrifugal spinning buckets in said compartments, air ducts connecting said compartments, and refrigerating means for regulating the relative humidity of said compartments.

3. In an apparatus for the manufacture of artificial threads, a plurality of individual compartments, centrifugal spinning buckets in said compartments, and refrigerating means surrounding each compartment for regulating the relative humidity therein.

4. In an apparatus for the manufacture of artificial thread, a plurality of individual compartments, centrifugal spinning buckets in said compartments, air ducts connecting said compartments for maintaining the circulation of the air in said compartments, and refrigerating means surrounding each compartment for regulating the relative humidity therein.

5. The method of preventing the formation of crystals in a spinning bucket compartment which comprises lowering the temperature of said compartment to increase the relative humidity therein.

6. The method of preventing the formation of crystals in a series of spinning bucket compartments which comprises lowering the temperature in said compartments to increase the relative humidity therein, circulating the air in said individual compartments, and circulating the air through said series of compartments.

7. The method of preventing the formation of crystals in a spinning bucket compartment which comprises lowering the temperature to produce a relative humidity of at least 8. The method of preventing the formation of crystals in a spinning bucket compartment which comprises passing a refrigerating medium in proximity to said compartment to increase the relative humidity in said compartment.

9. The method of preventing the formation of crystals in a spinning bucket compartment which comprises passing a refrigerating medium in proximity to said compartment to lower the temperature thereof sufficiently to produce a relative humidity of at least 75% in said compartment.

PAUL E. HARRISON. 

